The frequent occurrence of ACL injury and subsequent surgical reconstruction of the ligament make ACL failure a prominent national health concern. This biomechanics research study examines the injury mechanisms of the ACL in sports, recreation, and exercise-related activities with the ultimate goal to evaluate interventions and reduce the risk of injury. No study has been found that used combined loading to cause the ACL to fail or that generated concurrent injuries that often accompany ACL failure. Therefore, while existing studies have provided important insights into the normal strain on the ACL and the effects of ACL injury on the knee, a better model to study the injury mechanisms of the ACL and bridge the gap between experimental in-vitro strain data and clinical failures is desired. The specific aim of the proposed work is to develop and demonstrate a loading and motion protocol to repeatedly rupture the ACL of a cadaver by dynamically simulating a loss-ofcontrol cutting maneuver that causes similar injuries to the knee as seen clinically. A better understanding of the mechanism of ACL injury will provide information to be used to develop preventive interventions and evaluations of interventions and post-injury reconstructions. One predisposition that will be examined is that subjects with smaller femoral notch widths, independent of gender, will require lower magnitudes of loads to cause failure of the ACL during a simulated cutting maneuver. Work indicates that the greatest potential for ACL injury occurs during initial weight acceptance due to the combined anterior force, internal torque, and valgus moment. A dynamic knee simulator will be used to apply the tri-axial physiological loading from a cutting maneuver to eight cadaver knees. To rupture the ACL, the failure profile will be repeated and increased until the ACL breaks or the condition of the knee stabilizes, determined by repeated laxity results. Strain in the ACL will be recorded during these tests using small transducers attached to the ligament. A sports medicine physician will evaluate the condition of the knee and compare it to clinical observations to determine how similar the injuries are to clinical cases. The broad implications of this work are that the failure methodology developed will enable researchers to perform studies not previously possible, specifically investigations of correlations between ACL injury and knee anatomy and characteristics